1. Field of the Invention
The present invention relates to a method and apparatus for controlling the movement of a cursor on the screen of a computer terminal in general and to a method and apparatus for controlling the movement of a cursor on the screen of a computer terminal in a manner which corresponds to the movement of a finger in a fan-shaped field which extends vertically from a terminal keyboard in particular.
2. Description of Prior Art
Various pointing devices are used by the operators of computer terminal equipment for controlling cursor speed of movement and position on a display. Changes in cursor position may be made between arbitrary points on the display or relative to an object appearing on the display. The object may be an item to be selected from a menu, a word or a character in text, or an element in a design (a musical note or a circuit component, for examples).
Currently used cursor-positioning techniques and apparatus comprise: cursor-movement keys (often marked with up-, down-, right-, and left-pointing arrows), joysticks, trackballs, mice, pucks, light pens, touch screens, and touch tablets. Digitizing tablets can also be used; however, these are usually higher-precision devices and are intended primarily to enter absolute coordinate values into a computer rather than just to position a cursor relative to existing displayed material.
In practice, all of the competing techniques have advantages and disadvantages, but none are as satisfactory, especially to the untrained user, as the nearly unconscious act of a handwriter who moves the tip of a pen or pencil to a point of interest.
Cursor movement keys are generally acknowledged to be the fastest available technique for text editing, at least with a proficient typist editing from a marked draft. Less dedicated users are better off with a mouse; it is more intuitive, requires less training and practice, and is less distracting. However, the mouse is not without its drawbacks. It requires clear deskspace in which to operate and further, in each operation, one must first find the mouse, move it, and then refind one's hand position on the keyboard.
In general, all of the prior known alternative cursor-positioning techniques and apparatus, with the exception of a small, thumb-operated trackball located on a keyboard, share the problem of losing one's place on the keyboard.